"Previously, people were only able to grow a few square millimetres of high mobility graphene at a time and it required very high temperatures, long periods of time and many steps," said Professor Nai-Chang Yeh. "Our new method can consistently produce high mobility and nearly strain-free graphene in a single step in just a few minutes without high temperature. We have created sample sizes of a few square centimetres and, since we think that our method is scalable, we believe that we can grow sheets that are up to several square inches or larger, paving the way to realistic large scale applications."
The process uses a hydrogen plasma to clean the surface of a sheet of copper, after which the introduction of methane starts the growth of graphene in a more orderly way than the high temperature approaches used previously.
The ability to produce graphene without the need for active heating not only reduces manufacturing costs, but also results in a better product because fewer defects are generated. "Typically, it takes about 10 hours and nine to ten different steps to make a batch of high mobility graphene using high temperature growth methods," Prof Yeh noted. "Our process involves one step and it takes five minutes."
Further investigations have shown that graphene made using the new technique is of higher quality, is stronger and it has the highest electrical mobility yet measured for synthetic graphene.
A scaled up version of the plasma technique could open the door for new kinds of electronics manufacturing, Prof Yeh said. "In the future, you could have graphene based mobile phone displays that generate their own power."
